FREE RADICALS BY MASS SPECTROMETRY: XIII. THE MERCURY PHOTOSENSITIZED DECOMPOSITION OF ALLENE AND BUTADIENE: THE C3H3 RADICAL

Abstract

The Hg(3P1) photosensitized decomposition of allene leads to the formation of a C3H3 radical. The reaction of this radical with added methyl radicals shows it to have the propargyl (ĊH2—C≡CH) structure rather than the alternative allenyl (CH2=C=ĊH) structure. The dissociation of 1,2-butadiene proceeds by two modes, one to give H2 + C4H4, and the other a split into CH3 and C3H3 radicals. The dissociation of 1,3-butadiene leads to the same final products, a shift of a hydrogen atom being required for the split into free radicals. No evidence was found for a dissociation of 1,3-butadiene into two vinyl radicals. Considerable polymer formation occurred with all three compounds.